The present invention deals with a turboreactor or turbojet engine comprising at least a precombustion chamber, a combustion chamber, means for directing combustion gases from the precombustion chamber into the combustion chamber, an air compressor, and means for dividing the air flow from the air compressor while guiding it in the combustion chamber.
Document GB-A-650,661 discloses a turboreactor comprising at least one compressor drawing and compressing air so as to form at least one principal compressed air flow, one or more combustion chambers, at least one means for supplying fuel to the combustion chamber(s), at least one means for supplying an oxidizing means or air in the combustion chamber(s), and at least one turbine receiving the combustion gases of the combustion chamber(s), said turbine driving the compressor and being followed by an outlet nozzle.
In this known turboreactor, the principal or major airflow of the compressor is essentially used for the combustion of fuel and is introduced, at reduced velocityand in a turbulent form, in the combustion chamber(s) before its use for the necessary mixing for ensuring the complete combustion and its passage through the turbine. The necessary perturbation of the principal air flow is required in order to ensure a substantially homogeneous mixing with the fuel, the production and the stability of the flame, the complete progression of the combustion, with an admissible temperature for the walls of the chamber(s) and for the turbine blades.
Other turbojet engines are disclosed in U.S. Pat. Nos. 5,473,881, 3,691,766, 4,168,609 and 5,177,956, the content of which is incorporated by reference.
In all these known engines, the combustion gases of a prechamber are not directed in the combustion chamber between two distinct compressed air flows coming from an air compressor.
In order to avoid these drawbacks, the turboreactor or turbojet engine of the invention comprises at least one precombustion chamber comprising one or more means for supplying fuel and oxidizing medium (preferably air). The precombustion chamber comprises or is associated with means for directing the combustion gases from the prechamber into one or a plurality of combustion chambers. Advantageously, the means for directing the combustion gases from the prechamber into the combustion chamber is a part of the prechamber. The prechamber or precombustion chamber comprises advantageously a mixing and precombusting zone fuel-oxidizing means(preferably fuel-air), possibly preceded with a premixing zone fuel-oxidizing means (air) substantially without combustion.
The turboreactor of the present invention, with a prechamber with a reduced volume which is advantageously bent with respect to the combustion chamber, has the advantage to enable a reduction of the axial overall length (in the longitudinal axis) of the turboreactor, and also a reduction of pressure losses of the gases along their path through the zones necessary for a complete combustion. Moreover, the turboreactor comprises a means for directing at least a portion of the main stream of air flow of compressed air from the compressor in one, several, or each of the plurality of combustion chambers, said means being arranged in relation to the means for supplying the combustion gases from the prechamber in one, several or each of the plurality of combustion chambers so that at least a portion of the main stream (FP) of compressed air from the compressor which is guided into one, several or each of the plurality of combustion chambers creates an aspiration of the combustion gases from the prechamber (a depression formed in the combustion chamber extracting combustion gases from the prechamber) in order to ensure at least the transit of the gases from the prechamber to the combustion chamber and also for obtaining in said combustion chamber, a complementary, advantageously substantially complete combustion of the fuel which was not burnt in the precombustion chamber, such aspiration or sucking being advantageously combined with a mixing of the combustion gases with a portion of the main stream of compressed air in one, several or each of the plurality of combustion chambers. Advantageously, said means is agenced or adapted for ensuring also an air supply into the precombustion chamber.
It is clear that the turboreactor may comprise one or several precombustion chambers or prechambers of combustion associated to one or several combustion chambers. So, for example, the turboreactor comprises several distinct precombustion chambers whose combustion gases are directed in only one combustion chamber and/or several distinct precombustion chambers whose combustion gases are directed in several distinct combustion chambers, in particular whose combustion gases of each prechamber are directed in one distinct combustion chamber. In the present specification, xe2x80x9cprechamberxe2x80x9d or xe2x80x9cprecombustion chamberxe2x80x9d means one or several distinct prechambers or precombustion chambers, in particular placed in parallel, while xe2x80x9cchamber or combustion chamberxe2x80x9d means one or several combustion chambers, in particular placed in parallel.
The turboreactor or turbojet of the invention has means for directing at least a portion of the main stream of compressed air from the compressor in the combustion chamber, said means having a series of passages dividing the main stream into a series of compressed air flows flowing in the combustion chamber. Said passages are designed with respect to the means directing the combustion gases from the precombustion chamber to the combustion chamber so that each mean directing the combustion gases from the precombustion chamber into the combustion is located between two passages dividing the main stream of compressed air and so that the compressed air flows issued from the division of the main air flow creates a depression in the combustion chamber with respect to the precombustion chamber and a suction of the combustion gases from the precombustion chamber into the combustion chamber. In said turbojet engine, a series of distinct flows of combustion gases from the precombustion chamber(s) (such as more than 3 flows, advantageously more than 4, preferably more than 5, most preferably more than 6, such as 7,10, or even more than 10) are formed. Said flows are separated the one from the other by a compressed airflow coming from the compressor.
Advantageously in the turboreactor or turbojet engine of the invention, the compressor and/or the means for directing at least a portion of the main stream of compressed air or principal compressed air flow from the compressor into the combustion chamber are arranged to ensure for the portion of the main stream entering the chamber at a velocity which is at least higher than the velocity of the gases flowing out of the prechamber, advantageously at least two times as high as the velocity of the gases flowing out of the prechamber, preferably at least five times as high as the velocity of the gases flowing out of the prechamber and in order to ensure that the combustion chamber is in depression at least in relation to the precombustion chamber, preferably in relation to the precombustion chamber and the surroundings of the precombustion chamber.
Advantageously, the means directing at least a part of the main stream or principal flow of compressed air coming from the compressor consists of a wall of the means ensuring the passage of gases from the prechamber to the chamber or of a wall associated to the means ensuring the passage of gases from the prechamber to the chamber.
Advantageously, the means directing at least a portion of the main stream or principal flow of compressed air flowing from the compressor to the combustion chamber is designed or adapted so that substantially all the compressed air flow flowing out of the compressor is directed to flow in the combustion chamber without being significantly disturbed either in velocity, either in direction. This embodiment is advantageous as it enables to reduce pressure losses or pressure drops of the air flow and gas flow in all the means necessary to the combustion, said pressure losses being not negligible for classical combustion chambers. For example, the velocity of the principal or main flow of compressed air flowing through the combustion chamber is at least 75% of the initial velocity of the principal flow entering in the combustion chamber, in particular at least 85% of the initial velocity of the principal flow entering in the combustion chamber during the passage, preferably substantially equal to the initial velocity of the principal flow entering in the combustion chamber
According to an advantageous embodiment, in relation to the position of the means (forming advantageously a part of the prechamber) for directing the combustion gases from the prechamber into the combustion chamber, the means for supplying fuel and oxidizing medium (such as air) in the prechambex are located closer to the turbine of the turbojet engine or are spaced a longer distance from the compressor. In other words, the prechamber with its means for supplying fuel and oxidizing medium (preferably air) is advantageously designed or adapted so that the flow of combustion gases in the prechamber is directed in a direction substantially opposite to the gas flow in the combustion chamber. This embodiment is advantageous as the axial or longitudinal length of the chambers is reduced, while enabling however all the essential phases of the process, namely injection, mixing fuel-oxidizing medium (air), inflammation, mixing, precombustion and combustion.
In the turboreactor or turbojet engine of the invention, liquid fuels such as petrol, benzine, kerosene, etc., as well as gazeous fuel such as methane, etc. can be used. When using a liquid fuel, it is advantageous that its supply to the prechamber is made by a pipe in contact with a hot part of the turboreactor so as to ensure a natural vaporization of the fuel at the fuel injection in the prechamber.
As oxidizing means, air coming from the compressor and/or external compressed or pressurized air (not coming from the compressor of the turboreactor) and/or any appropriate oxidizing medium (such as oxygen) is advantageously used. In particular, for the combustion in the prechamber or precombustion, air directly coming from the compressor and/or air coming from the main flow of compressed air is at least partly used. Air coming from the compressor can be directed in the prechamber without flowing through the combustion chamber, said air being for example mainly directed by one or more ducts, pipes or openings, advantageously substantially close to the axis of the turboreactor, in the prechamber through the sides or walls of the prechamber directed towards the axis of the turboreactor and/or the front side or wall (side or wall directed towards the compressor) of the prechamber and/or the rear side or wall or bottom of the prechamber (side or bottom directed towards the turbine).
According to a possible embodiment, the turboreactor or turbojet engine of the invention has means ensuring a passage for compressed air flowing from the compressor into the prechamber, said means being adapted or designed so that the ratio between the stream or flow of compressed air flowing from the compressor and into the prechamber and the stream or flow of compressed air flowing from the compressor and into the chamber is smaller than 1/5, advantageously smaller than 1/8, preferably smaller than 1/10, more preferably less than 1/20. The ratio will be adjusted as required, in particular in function of the maximum admissible turbine temperature.
According to a detail of a preferential embodiment, the turboreactor has means ensuring a passage for combustion gas from the combustion chamber into the prechamber, said means being arranged or designed so that gases from the chamber flow into the prechamber between the fuel supply means in the prechamber and the means which form advantageously part of the prechamber and which direct the combustion gases from the prechamber into the combustion chamber.
The passage of gases from the combustion chamber to the prechamber and/or the passage of air directly coming from the compressor into the prechamber enables to ensure the precombustion by use of a better mixing of fuel-oxidizing medium(air) in the prechamber and/or by use of the progressive increase of the air proportion during the precombustion step.
According to another advantageous detail, the means (forming advantageously a wall of the prechamber) for directing the combustion gases of the prechamber in the combustion chamber comprise or form means dividing the stream or flow of compressed air flowing from the compressor in one or more first stream(s) or flow (s) entering into the chamber and in one or more second stream(s) or flow(s) supplying the prechamber through openings of its envelope, said second stream(s) or flow(s) having a lower flow rate than the first stream(s) or flow(s), in particular well below the first flow(s) or stream(s) so as to enable a limited volume or size for the prechamber. The prechamber comprises advantageously means for directing said second stream(s) or flow(s) or a portion thereof in the prechamber and/or in one or a plurality of means for directing the combustion gases from the prechamber into the combustion chamber, for supplying said prechamber or means with oxidizing medium (air).
Preferably, means dividing both air flows is adapted so that the ratio second air flow(s)/first air flow(s) is lower than 1:5, advantageously lower than 1:8, preferably lower than 1:10, in particular lower than 1:20.
It has also been found advantageous that said means direct compressed air in the prechamber or in its part forming the means directing the combustion gases of the prechamber into the chamber. This air supply ensure a better mixing air and gases with the fuel permitting the precombustion. The means supplying compressed air is or forms, for example, one or more external compressed air injectors or nozzles or one or more openings bored or present in the wall(s) of the envelope of the prechamber. Due to the suction or drawing force exerted on the gases of the prechamber by the power and/or high relative velocity of the main or principal compressed air flow flowing in the combustion chamber, air coming from the compressor is sucked through one or more openings bored or present in the envelope of the prechamber.
When the turboreacror or turbojet engine is provided with means ensuring a passage for the gases from the chamber into the prechamber, said means are advantageously arranged such as not to be located in the wake or path or extension of the stream or flow of gases leaving the means for guiding the gases from the prechamber into the combustion chamber. This enables to ensure that gases passing from the combustion chamber into the prechamber contain only a few combustion gases or are essentially constituted of air coming from the principal compressed airflow.
According to an advantageous detail of an embodiment, at least a part or portion of the prechamber, particularly at least one part of its means guiding its combustion gases from the prechamber into the chamber, is provided with a lining or coating or layer containing at least a combustion catalyst.
According to an advantageous characteristic of the turboreactor or turbojet engine, the compressor includes a stator which is at least partially rotatable (for example fully rotating), in particular at least partially contrarotatable (for example fully contrarotating) in relation to the rotor, possibly fixedly attached to an external fan or the rotor of an external auxiliary compressor. According to a possible embodiment, the stator comprises a fixed part and a rotating part, in particular a contrarotating part, said rotating or contrarotating part being related or connected to an own turbine. The outer wall of the rotating stator, particularly contrarotating, is possibly joint to a rotor of an auxiliary compressor or an auxiliary fan or to elements forming an auxiliary compressor or fan. This auxiliary compressor or fan forms an external compressor or fan which is advantageously placed into the axial or longitudinal limits between the axial ends of the principal or main compressor or fan, so as to reduce the volume in its longitudinal direction. The air flowing out of the auxiliary compressor or fan advantageously serves or acts for diluting the gases escaping the central part of the turboreactor, enabling therefor an improvement of the propulsion or jet output.
According to a detail of a turboreactor, the compressor includes a stator provided with blades and a rotor provided with blades, the body of the rotor and/or of the stator comprising a layer or coat of thermoplastic material or being made of a thermoplastic material in which the blade bases or roots made of a heat conductive material (preferably an electrically conducting material, in particular in metal or anyone metal alloy suitable for the compressor blades and suitable to stick to the thermoplastic material) are embedded.
The invention relates also to a turboreactor or turbojet engine of the type disclosed in the first paragraph of the present specification, in which the compressor comprises a stator and a rotor (rotating with respect to the stator and with respect to the frame of the turboreactor), the stator being also at least partly rotating (for example wholly rotating) with respect to the frame and at least partly contrarotating with respect to the rotor. This design permits to compress more or less the air flowing through the compressor, without requiring high rotational velocities for the rotor and its turbine, this enabling to reduce the number of stages of the compressor and therefor its size. The rotating part of the stator is joined to its own turbine. This turboreactor is constituted of an envelope, a compressor to compress air for forming at least a main or principal compressed air flow, a combustion chamber, at least means to supply fuel into the combustion chamber, at least one means for supplying air or an oxidizing medium into the combustion chamber and at least two turbines receiving combustion gases from the combustion chamber, the compressor comprising a stator (totally or partly rotating with respect to the frame) and a rotor (rotating with respect to the stator and to the frame), the rotating part of the stator being joined to one or more stages of a turbine, the rotor being joined to one or more other stages of another turbine. The stage(s) of the rotating stator turbine and the stage(s) of the rotor turbine are designed so that the stator contrarotates with respect to the rotor. Advantageously the rotating part of the stator is joined to a fan or constitutes a frame or body of an auxiliary compressor rotor on its outer side or wall or face directed towards the envelope for creating an outer (additional) air flow or an (additional) air flow along the wall of the envelope, said additional air flow being mixed at the outlet of the turboreactor in order to increase the propulsion or jet output, without significant increase of the overall length of the main or principal compressor.
Another object of the invention is a method for fixing heat conducting elements or elements into a thermoplastic coat, in particular to form elements provided with blades or fins, and more specifically in order to construct a rotor and/or a stator of a compressor.
This process intended to fix at least one end of a heat conducting element into a thermoplastic coat or layer consists at least to heat at least the end of the element to a temperature higher than the softening temperature, preferably the melting temperature of the thermoplastic material, and to press the element into the coat in order to enable the penetration of the end of the element into the thermoplastic coat or layer. Particularly the end of the element is heated to a temperature 10 to 50xc2x0 C. higher than the melting temperature of the thermoplastic material without reaching a carbonization step (for example by heating below the carbonization or degradation temperature or by submitting the thermoplastic material to a temperature higher than the carbonization temperature during a short time).
Advantageously, the thermoplastic coat or layer is provided with holes, recesses or cavities or threads or grooves at the places where the end of the element(s) has(have) to be inserted. These holes, cavities, recesses, grooves or threads permits the softened or melted thermoplastic material to flow therein when the blade penetrates into the thermoplastic material, These cavities, holes, grooves, recesses or threads receiving this flow of softened or melted thermoplastic material as well as the end of the element to be inserted during its penetration in the thermoplastic coat or layer.
For inserting elements, said elements have advantageously heat conductive elements having a softening point higher than the melting temperature of the thermoplastic coat or layer. Particularly, this softening or melting point of the heat conductive element to be inserted into the thermoplastic coat or layer is at least 100xc2x0 C. higher than the melting temperature of the thermoplastic coat. The end of the element, advantageously metallic, which is inserted in the thermoplastic coat or layer, is advantageously shaped or worked so that said end has a smaller section than the body of the element, for example for its heating and/or for its positioning.
Instead of using complex injection moulds with places for inserts, or to proceed to local heating of the thermoplastic coating or layer obtained by the complex means of ultrasonic devices, it is advantageously processed to the heating of the element or the end thereof by conduction, convection or radiation. Preferably, this heating is carried out by the flow of electrical current through the element.
Particularly, a subject matter of the invention is a process for placing blades made in electrical conducting material on a stator and/or a rotor of a turboreactor, particularly a turboreactor according to the invention, this stator and/or rotor being provided with a coating or layer of thermoplastic layer or made of thermoplastic material, in which the end of the blade to be inserted into the thermoplastic coating or layer is heated at a temperature higher than the melting temperature of the thermoplastic material, and by pressing the end of the blade against the thermoplastic coating or layer in order to insert this end into the thermoplastic coating or layer.
This process is not only an easy and simple process, but it also enables to constitute all or part of the rotor of the compressor in a light material permitting it to rotate more rapidly without reaching to early its critical rotation velocities.
Preferably, the end of the element is heated to a temperature 10xc2x0 C. to 50xc2x0 C. higher than the melting temperature of the thermoplastic material without to carbonize it (temperature less than carbonizing temperature or heating very shortly above this temperature).
Accordingly, the thermoplastic material is provided with holes, hollows, grooves, cavities, etc. Said holes, grooves, recesses, cavities, hollows, etc. are preferably adjusted in order to receive the melted thermoplastic flow when the (heated) end of the blade penetrates into the thermoplastic material, they also serves as vent or air escaping holes and/or as means for facilitating the positioning of the blade.
For example, the cavities, grooves, holes, recesses, hollows, etc. have a chamber adapted for receiving softened or molten thermoplastic material when the blade is inserted into the thermoplastic coating or layer. In this process, use is advantageously made of heat conducting elements having a softening point or melting point above the melting temperature of the thermoplastic coating or layer. In particular, the softening temperature or melting temperature of the heat conducting element to be inserted into the thermoplastic coating or layer is at least 100xc2x0 C. higher than the melting temperature of the thermoplastic coating or layer. According to an embodiment of the process, the end of the element, advantageously metallic, which is inserted in the thermoplastic coating or layer, is advantageously worked or shaped so that said end has a portion with a smaller section than the body of the element, notably for facilitating its heating and/or its positioning.
Details and characteristics of the invention will appear from the following detailed description in which reference is made to the attached drawings.